During the production of continuous filamentary or spun yarns, for example, the yarns are often conventionally subjected to a drawing or stretching process under tension. This stretching process is followed by a partial or complete relaxing of the yarn to produce the desired physical characteristics, such as a reduced shrinkage propensity in the processed yarn or some other effect, i.e., bulking or crimping of the filaments forming the yarn. Such yarns may have an inherent tendency to retract into a crimped form under low tension. Heat may also be used to assist this process.
Conventionally, the relaxation of yarn has been accomplished by a type of batch process wherein the yarn is temporarily collected in some form of can or box which allows a degree of contraction to take place such as seen in U.S. Pat. No. 3,470,587 by Kincaid titled "Planetary Coiler." Other processes are also known such as continuously subjecting the fed yarn to treatment with a hot fluid in some form of jet device such as seen in U.S. Pat. No. 3,644,968 by Elliott et al. titled "Apparatus For Relaxing Yarns." These prior methods, however, involve a relatively slow batch process, primarily provide only one pattern or type of crimp in the yarn, provide limited production output, and provide little control over the production process.